The aim was to explore existential suffering n physicians caring for terminally ill cancer patients. We performed qualitative analyses of 30 physician-reported descriptions of the clinical experience of caring for terminally ill cancer patients. Analyses were conducted using descriptive phenomenology to clarify the meaning of physicians’ experiences, guided by the three dimensions of Murata’s human being model. In their descriptions, all physicians mentioned existential suffering related to incompetence, and three themes were identified: 1) physicians who focus on the limitations of what they can achieve with curative or palliative treatment feel a sense of incompetence; 2) physicians who focus on difficulties in caring for patients with existential suffering feel a sense of incompetence; and 3) physicians who focus on environmental factors, such as work overload and insufficient communication skills training, experience a sense of incompetence. Physicians experience a sense of incompetence when they face treatment limitations and/or difficulties in caring for patients with existential suffering.